Over 100 cases of human temporal lobe epilepsy have been studied, both with and without chronic indwelling electrodes, followed by lobectomy. The hippocampal tissues (and oter portions of cortices) have been investigated by light, Golgi and ultrastructural techniques and, aside from obvious lesions, changes such as axonal degeneration, contraction of dendritic geometry, loss of dendritic spines and development of dendritic varicosities, have been found. These alterations suggest ongoing disease in certain cases of temporal lobe epilepsy. Ancillary studies have been carried out on the use of chronic indwelling electrodes as prostheses inhibitory to seizure patterns in the monkey (although these have been and are currently being emplaced in man) and neural damage has been found when the charge activating the electrodes rises above 0.5 c/pH over 205 hours of stimulation (10 pps). Also in another study, cobalt has been used to directly injure and induce in limbic structures a variety of ictus. The alkaloid bicucculine HCl is being used to induce status epilepticus. The latter agent does not appear to induce injury to the hippocampal cortex in the cat (over 300 minutes of seizures followed by 120 minutes of rest) when arterial pH, fluid balance, body temperature and respiration are normally maintained. Studies of synaptosomes of the human temporal cortex are of necessity opportunistic and data obtained thus far is fragmentary. BIBLIOGRAPHIC REFERENCES: Brown, W.J., Babb, T.L., Soper, H.V., Lieb, J.P., Ottino, C.A., and Crandall, P.: Tissue Reactions to Long-Term Electrical Stimulation of the Cerebellum in Monkeys. J. Neurosurg. June, 1977 (in press). Babb, T., Soper, H., Lieb, J., Brown, W.J., Ottino, C.A., and Crandall, P.: Electrophysiological Studies of Long-term Electrical Stimulation of the Cerebellum in Monkeys. J. Neurosurg., June, 1977 (in press).